Boats



sept. 19, 1967 F. H. M. u:Y MAREC BOATS Filed Feb. 4, 1965 Sept. y19, 1967 F. H. M.. L E `MAREC:

BOATS Filed Feb. 4, 1966 F. H. M. LE MAREC Sept.I 19, 1967 BOATS 3 Sheets-Sheet s Filed Feb. 4, 1966 f7 rrys.

United States Patent O" 3,342,154 BOATS Francois Henri Marie Le Marec, Moussy-le-Vieux,

France, assgnor to Navili S.a.r.l., Le Mesnil-Amelot, France, a corporation of France Filed Feb. 4, 1966, Ser. No. 525,013 Claims priority, application France, Feb. 8, 1965,

Claims. (ci. 114-665) ABSTRACT OF THE DISCLOSURE A boat hull in catamaran form provided at the stern with two spaced-apart coffers projecting from the main body of the hull and having keels positioned below the main body, to enable the boat to fioat mainly or solely on the two coffers, particularly at high speeds.

The present invention concerns a boat with improved stability and ease in handling and with various other improvements in relation to boats of known types.

Some of these improvements are partly the result of the catamaran shape of part of the hull of the boat. The word catamaran will hereinafter be used to refer to a hull shape which defines, with at least certain water levels, several separate oating zones extending parallel with the length of the boat and located side by side.

The advantages of the catamaran shape from the point of view of transverse stability and resistance to yawing are known. These are accompanied by certain disadvantages, including the necessity of a larger turning radius.

Furthermore, high-speed boats which plane over the water have an inherent instability resulting from the fact that the thrust centre of the water is in front of the motive thrust of the propellor. Any lack of alignment between these two opposing forces tends to become accentuated and balance is re-established by jolts and jerks by the `action of the weight of the boat or else by the reverse action of the vertical thrust of the water on the hull.

Moreover boats usually produce a V-shaped furrow and displace the water sideways from the stem, resulting in a loss of energy. l

The present invention envisages means of obviating or reducing the above disadvantages and to this end proposes a catamaran hull comprising two rear coffers which, behind and on both sides of the propellor, form prolongations of two separate floating zones formed over the rest of the hull. In a hull thus arranged the two separate float, ing zones are gradually resorbed or readsorbed from the front asthe boat is gradually lifted up by speed at which -it is travelling; thus, the relative size of the immerged portions to the rear of the propellor increases gradually and without interruption.

The boat may further comprise a floating zonelocated in the longitudinal axis and arranged so that it too iSI gradually resorbed from front to rear.

The separate floating zones thus arranged form one or more tunnels. As these are partly filled with air they are particularly well suited to receive and channel back any water displaced at the bows. This water empties into a space partly bounded by the rear coffers and it contributes to the satisfactory feeding of the propellor.

The various objects and features of the invention and the resultant advantages will be revealed in the description which now follows of an embodiment of the invention chosen by way of example. The description refers to the accompanying diagrammatic drawings, in which:

FIG. 1 is a longitudinal profile of the boat;

FIG. 2 is a view from below with water lines 11, 12 and 13;

ice

FIG. 3 is a view Ifrom above;

FIGS. 4 and S are cross sections;

FIG. 6 is a perspective view.

In the embodiment shown by way of example in the drawings the boat according to the invention is made up of a monocoque unit 1 extending from the prow 2 to an intermediate board 3, and two coffers 4 and 5 coupled to the board 3. The end partitions 6 and 7 of the coffers 4 and 5 form the rear board of the construction.

The monocoque unit 1 has two differently shaped portions. The front portion, associated with the stem 8, extends from the prow 2 to a point in the vicinity of the cross sectional plane IV. The shape of this front portion 1 is shown by the profile in sectional plane Il shown in FIG. 44. In accordance with this profile the hull consists, on both sides of the stem 8, of planking 9 which rises continuously from the stem to the edge 10 of the deck.

The shape of the rear portion 1B of the monocoque unit 1 generally follows the arrangement shown in sectional plane VI in FIG. 4. That is to say, on each side of the keel 11 the hull has a bottom 12 with the profile of an upwardly curved arch which redescends to join the planking 13 by means of abilge keel14; the top of the arch 12 is thus at a higher level than the keel 14, and can escape some water level; it therefore allows the rear portion 1b to rest on two lateral floating zones extending The planking 13 has a projecting longitudinal ridge shown at 15 in FIG. 1, thus producing a break in the transverse profile in sectional plane VI in FIG. 4; the portion 13a of the planking located labove the breaking point 15 is concave over its external surface, thus backing 0E from the lower portion of the planking shown at 13b.

The bilge keels 14 extend to in front of the sectional plane III to form two lateral stems in the bows region 1a; these are complementary to the stem 8 and connected thereto by concave hull planking shown at 16 in cross sectional planes II and IV. This permits a gradual transition between the two types of profile, exemplified by sectional planes II and VI.

It will be seen from FIG. 1 that the central keel 11 is substantially horizontal whereas the bilge keels 14, inclined from end to end, rise towards the front and attack the water levels at an angle. The Archimedes thrust produced at keels 14 thus starts from zero and it gradually increases towards the stern. l

FIG. 1 also shows that the bilge lkeels 14 drop below `the keel 11 from an intermediate point thereon in the catamaran.

It will be seen from FIG. 2 that the keels 14 and ridges 15 are extended as far as the rear board 6 to 7, and from FIG, 5 that the portions 12, 13a and 13b of the monocoque unit merge smoothly into corresponding similar portions of the stern coffers.

The space between these two coffers is occupied by a motor 17 mounted on the board 3. The propellor 18 is in front of the rear board 6 to 7.

The embodiment just described makes it possible to concentrate the oating zones at points widely spaced from the hull. Once the boat has sewn up by the action of the speed and the force of the wind on its stem, it rests solely or almost entirely on two widely spaced rear skids formed by the keel portions 14 associated with the stern coffers. The result is that only a small surface is wetted and that the boat has an excellent posture as well as good speed and stability when tacking.

At intermediate speeds the boat drops back on to a 3 point hull, the third point of support or skid being provided by the central keel.

Transmission from the 3 point hull to the 2 point hull is made smoothly, by total resorption of the central supporting zone, taking place progressively from front to rear, and accompanied by partial resorption of the two lateral supporting zones in the same direction. Moreover lengthwise resorption of the central zone is attended by a simultaneous gradual reduction of its width. Transition from the 3V point to the 2 point support thus takes place without any abrupt change. This gradual resorption of the supporting zones is enhanced by any tendency of the boat to tilt upwards from back to front relatively to the horizontal.

On the other hand, the inclination of the bilge keels makes it possible to attack the water level at an angle and this can be done as soon as the boat has cast off. Casting of is made easier, and the gradual attack by the bilge keels allows for very good acceleration and easy gliding.

The inclination of the bilge keels makes it possible to form catamaran elements whose section gradually increases towards the rear starting from zero.

The various catamaran elements are interconnected, at least at a part of their length, by higher portions with an arched profile. These form longitudinal tunnels which allow air and water to escape to the stern. The stability of the boat is considerably increased in the face of wind and water thrusts; besides, only a small amount of water is forced back onto the sides and resistance to the forward movement is thereby reduced. The water which is forced back sideways shows no tendency to come on board, for it can easily leave the hull as a result of the backing off at the top of the latter.

Evacuation of water into the stern in the space bounded by the two coffers ensures that the propellor is well supplied with water. Turbulence produced by the hull around the propellor is eliminated and so is cavitation.

The air discharge provided at the stern enables the stem to behave like a supporting fin or blade and the whole shape according to the invention may usefully be applied to hydroplanes. The provision of specific discharge points for air and water reduces drag and turbulence which may tend to slow down the boat.

The mounting of the motor, in a recess provided at the rear of the hull, has various advantages. The fact that the motor is in a forward position relatively to the rear board enables the weight of the motor to stabilise the boat and to help it to resume its normal position once it has sewn up to the point where it rests only on its rear board.

On the other hand the propellor Sinks in less deeply when the bows are raised, and the centre of thrust of the propellor remains close to the centre of horizontal thrust applied by the water to the rear skids.

Moreover the fact the motor is in a forward position makes it possible to reduce the distance between the propellor and the sliding skids to the rear and consequently to shorten the turns when going about.

The position chosen for the motor may be such that the propellor is right in front of the boat portions which are submerged when the boat reaches high speeds; this produces an effect similar to that produced by yfront wheel drive in land vehicles, with the advantages of improved stability when travelling in a straight line and increased safety when turning.

The invention has been described in its application to a motor boat but it may usefully be applied to boats of other types, for example to storm spankers.

In the latter case the submerged parts of the two bilge keels may be extended forwards to allow the storm spanker to bear on only one larger side skid instead of on two short stern skids.

The embodiment described by Way of example obviously has no restriction implications and may be varied in different ways and modified in detail.

In particular, the monocoque unit may be replaced by any equivalent unit operating as a catamaran, for example by a plurality of parallel coffers joined by diaphragms of arcuate profile to form tunnels for the discharge of air and water, the diaphragms being connected in front to a V-shaped fin or blade designed to reduce air resistance and possibly to lift up the boat.

I claim:

1. A boat hull comprising one main body and two spaced-apart coffers projecting from the rear of said main body, said main body having a central keel and two bilge keels, said coffers having two respective keel portions extending from said bilge keels and positioned below said central keel.

2. A boat according to claim 1 wherein said central keel is substantially horizontal.

3. A boat according to claim 1 wherein said bilge keels are inclined downwards from front to rear.

4. A boat according to claim 1 wherein said coffer keel portions extend smoothly from said bilge keels.

5. A boat according to claim 1 wherein said bilge keels extend partly above and partly below the central keel.

6. A boat according to claim 1 having a stern extending from the central keel.

7. A boat according to claim 1 having a stern extending farther forward than the bilge keels.

8. A boat 4according to claim 1 wherein the bottom of the hull forms an air and water tunnelling with an outlet discharging between the rear coffers.

9. A boat according to claim 1 wherein each side of the hull defines a ridge, located intermediate the corresponding bilge keel and deck line.

10. A boat according to claim 1, and a propeller located between the coffers and in front ofthe rear ends thereof.

References Cited UNITED STATES PATENTS 1,794,898 3/1931 Hillmann 114-665 3,135,976 6/ 1964 Winters 9 6 FOREIGN PATENTS 954,423 6/ 1949 France. 532,611 9/1931 Germany.

MILTON BUCHLER, Primary Examiner.

ANDREW H. FARRELL, Examiner. 

1. A BOAT HULL COMPRISING ONE MAIN BODY AND TWO SPACED-APART COFFERS PROJECTING FROM THE REAR OF SAID MAIN BODY, SAID MAIN BODY HAVING A CENTRAL KEEL AND TWO BILGE KEELS, SAID COFFERS HAVING TWO RESPECTIVE KEEL PORTIONS EXTENDING FROM SAID BILGE KEELS AND POSITIONED BELOW SAID CENTRAL KEEL. 